The Effect of Farmers’ Decisions on Pest Control 2 with Bt Crops: a Billion Dollar Game of Strategy

20 A farmer's decision on whether to control a pest is usually based on the perceived 21 threat of the pest locally and the guidance of commercial advisors. Therefore farmers in a 22 region are often influenced by similar circumstances, and this can create a coordinated 23 response for pest control that is effective at a landscape scale. This coordinated response is 24 not intentional, but is an emergent property of the system. We propose a framework for 25 understanding the intrinsic feedback mechanisms between the actions of humans and the 26 dynamics of pest populations, and demonstrate this framework using the European corn 27 borer, a serious pest in maize crops. We link a model of the European corn borer and a 28 parasite in a landscape with a model that simulates the decisions of individual farmers on 29 what type of maize to grow. Farmers chose whether to grow Bt-maize, which is toxic to the 30 corn borer, or conventional maize for which the seed is cheaper. The problem is akin to the 31 snowdrift problem in game theory; that is to say, if enough farmers choose to grow Bt maize 32 then because the pest is suppressed an individual may benefit from growing conventional 33 maize. We show that the communication network between farmers' and their perceptions of 34 profit and loss affects landscape scale patterns in pest dynamics. We found that although 35 adoption of Bt maize often brings increased financial returns, these rewards oscillate in 36 response to the prevalence of pests. A farmer's decision on whether to control a pest is usually based on the perceived threat of 40 the pest locally and the guidance of commercial advisors. Therefore farmers in a region are 41 often influenced by similar circumstances, and this can create a coordinated response to a 42 pest. This coordinated response, although not intentional, can affect ecological systems at the 43 landscape scale. Using the European corn borer as an exemplar system, we develop a 44 framework to explore the feedback mechanisms between pest populations and farmers' 45 decisions. We show that the form of communication network and the farmers' perceptions of 46 profit and loss influence the decisions made on pest control. Our work has implications for 47 other systems, whereby the ecology of a system is driven by individual decision makers 48 following similar heuristics and experiencing similar influences. …